ORA-01438: value larger than specified precision allowed for this column

create table tq84_ora_01438_test (
    col_1   number(2) not null,
    col_2   number(2) not null,
    col_3   number(2) not null,
    col_4   number(2) not null,
    col_5   number(2) not null
);
insert into tq84_ora_01438_test values(1, 12, 123, 12, 1);
--
-- ORA-01438: value larger than specified precision allows for this column

insert into tq84_ora_01438_test values(1, 12, 123, 12, 1);
--
-- SQL Error: ORA-01438: value 123 greater than specified precision (2, 0) for column 

select cast(123 as number(2)) from dual;